Wash. Rev. Code § 81.53.130
In the construction of new railroads across existing highways, the railroads shall do or cause to be done all the work of constructing the crossings and road changes that may be required, and shall acquire and furnish whatever property or easements may be necessary, and shall pay, as provided in RCW 81.53.100 through 81.53.120, the entire expense of such work including all compensation or damages for property or property rights taken, damaged or injuriously affected. In all other cases the construction work may be apportioned by the commission between the parties who may be required to contribute to the cost thereof as the parties may agree, or as the commission may consider advisable. All work within the limits of railroad rights-of-way shall in every case be done by the railroad company owning or operating the same. The cost of acquiring additional lands, rights or easements to provide for the change of existing crossings shall, unless the parties otherwise agree, in the first instance be paid by the municipality or county within which the crossing is located; or in the case of a state road or parkway, shall be paid in the manner provided by law for paying the cost of acquiring lands, rights or easements for the construction of state roads or parkways. The expense accruing on account of property taken or damaged shall be divided and paid in the manner provided for dividing and paying other costs of construction. Upon the completion of the work and its approval by the commission, an accounting shall be had, and if it shall appear that any party has expended more than its proportion of the total cost, a settlement shall be forthwith made. If the parties shall be unable to agree upon a settlement, the commission shall arbitrate, adjust and settle the account after notice to the parties. In the event of failure and refusal of any party to pay its proportion of the expense, the sum with interest from the date of the settlement may be recovered in a civil action by the party entitled thereto. In cases where the commission has settled the account, the finding of the commission as to the amount due shall be conclusive in any civil action brought to recover the same if such finding has not been reviewed or appealed from as herein provided, and the time for review or appeal has expired. If any party shall seek review of any finding or order of the commission apportioning the cost between the parties liable therefor, the superior court, the court of appeals, or the supreme court, as the case may be, shall cause judgment to be entered in such review proceedings for such sum or sums as may be found lawfully or justly due by one party to another.
RCW 81.53.130
Severability-1988 c 202: See note following RCW 2.24.050.